Light-emitting diode, and light-emitting diode package, light-emitting diode module and display device including the same

ABSTRACT

A light-emitting diode (LED) includes a light-transmissive substrate which has a first surface, an epitaxial structure which is disposed on the first surface, a first insulation layer, and a second insulation layer. The epitaxial structure has an upper surface opposite to the first surface, and a side wall interconnecting the upper surface and the first surface. The first insulation layer covers the side wall and the upper surface. The second insulation layer covers a portion of the first surface that is not covered by the epitaxial structure and the first insulation layer, and has a light transmittance greater than that of the first insulation layer. An LED package, an LED module, and a display device including the LEDs are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Chinese Invention Patent ApplicationNo. 201910996117.2, filed on Oct. 18, 2019.

FIELD

This disclosure relates to a semiconductor device, and more particularlyto a light-emitting diode (LED).

BACKGROUND

As compared with a conventional light-emitting diode (LED), a mini LEDhaving a relatively smaller size can be used directly in applicationssuch as backlight source and display devices. When a plurality of themini LEDs are used as a backlight source, delicate light adjustments maybe achieved, rendering a higher contrast ratio, a higher luminanceuniformity, and an excellent color expressivity. When the mini LEDs areused in a display device, a spacing between two adjacent ones of themini LEDs may be reduced to improve a resolution of the display device,thereby improving a visual impact thereof. The mini LED is usuallypackaged as a flip-chip, a face up chip, or a vertical chip, among whichthe flip-chip LED has become a major focus in the LED industry due toadvantages such as increased light extraction efficiency, increased heatdissipation ability, improved package reliability, and improvedproduction yield.

Referring to FIG. 1, a conventional flip-chip LED includes a substrate1, an epitaxial structure which includes a first-type semiconductorlayer 2, an active layer 3 and a second-type semiconductor layer 4sequentially disposed on the substrate 1 in such order, a contactelectrode 5 which is disposed on the second-type semiconductor layer 4,and first and second electrodes 7, 8 which are respectively electricallyconnected to the first-type and second-type semiconductor layers 2, 4.During a conventional packaging process for the flip-chip LED, apassivation layer 6 is usually formed to enwrap the epitaxial structure,so as to prevent electrical leakage caused by leakage of solder pasteduring the packaging process. In order to completely cover a side wallof the epitaxial structure, a portion of the epitaxial structure isusually removed by etching to partially expose the substrate 1, and thenthe passivation layer 6 is formed on an upper surface and the side wallof the epitaxial structure, and the exposed portion of the substrate 1(serving as a cutting region for separating the LED chips). Thepassivation layer 6 usually has an optical thickness that is equal to aninteger multiple of one-quarter of an emission peak wavelength of light(i.e., λ/4) emitted from the active layer 3, so as to ensure that thelight exits the LED from a surface of the substrate 1 opposite to theepitaxial structure. However, the thickness of the passivation layer 6covering the side wall of the epitaxial structure often does not meetthe requirements for light-transmittance due to a shadow effect ofexisting coating techniques for the passivation layer 6. Therefore, areflectance of the passivation layer 6 might be adversely affected, andlight emitted from the epitaxial structure might undergo secondaryreflection (illustrated by dotted arrow lines in FIG. 1) by thepassivation layer 6 that covers the cutting region of the flip-chip LED(i.e., the exposed portion of the substrate 1), which might result inlight loss. In addition, a width of the cutting region is generallyrequired to be at least 10 μm given the limitations of a conventionalscribing technique or a wafer breaking technique for obtaining separatedLED chips. As shown in FIG. 2, an area percentage of the cutting regionon the flip-chip LED increases to as high as 40% with a decreased sizeof the flip-chip LED, which might further increase light loss caused bysecondary reflection at the cutting region.

Furthermore, since the epitaxial structure and the cutting region arecovered by the passivation layer 6, a relatively high compressive strainmight be formed at the cutting region, and when a thickness of theflip-chip LED is reduced to be not greater than 60 μm, the flip-chip LEDmight suffer from severe bowing, which might result in breakage. With adecreased size of the LED and an increased area percentage of thecutting region, the bowing of the flip-chip LED might be intensified.Therefore, there is still a need to develop an LED exhibiting a reducedlight loss and compressive strain at the cutting region.

SUMMARY

Therefore, an object of the disclosure is to provide a light-emittingdiode (LED), a light-emitting diode package, a light-emitting diodemodule, and a display device that can alleviate or eliminate at leastone of the drawbacks in the prior art.

According to the disclosure, the LED includes a light-transmissivesubstrate, an epitaxial structure, a first insulation layer, and asecond insulation layer. The light-transmissive substrate has a firstsurface. The epitaxial structure is disposed on the first surface of thelight-transmissive substrate, and has an upper surface opposite to thefirst surface, and a side wall interconnecting the upper surface and thefirst surface. The first insulation layer covers the side wall and theupper surface of the epitaxial structure. The second insulation layercovers a portion of the first surface of the light-transmissivesubstrate that is not covered by the epitaxial structure and the firstinsulation layer. The second insulation layer has a light transmittancegreater than that of the first insulation layer.

According to the disclosure, the light-emitting diode package includes apackage substrate, and at least one light-emitting diode as mentionedabove which is disposed on the package substrate.

According to the disclosure, the light-emitting diode module includes apackage substrate, and a light-emitting array which is disposed on thepackage substrate and which includes a plurality of light-emittingdiodes that are arranged in a matrix. At least one of the light-emittingdiodes is the light-emitting diode as mentioned above.

According to the disclosure, the display device includes a plurality oflight-emitting diode modules as mentioned above.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the disclosure will become apparent inthe following detailed description of the embodiments with reference tothe accompanying drawings, in which:

FIG. 1 is a schematic view illustrating a conventional flip-chiplight-emitting diode (LED);

FIG. 2 is a diagram illustrating a relationship between a total area ofthe conventional flip-chip LED and an area percentage of a cuttingregion on the conventional flip-chip LED;

FIG. 3 is a schematic view illustrating a first embodiment of an LEDaccording to the disclosure;

FIG. 4 is a schematic view illustrating a second embodiment of the LEDaccording to the disclosure;

FIG. 5 is a schematic view illustrating a third embodiment of the LEDaccording to the disclosure;

FIG. 6 is a schematic view illustrating a fourth embodiment of the LEDaccording to the disclosure;

FIGS. 7 to 15 are schematic views illustrating consecutive steps of amethod for manufacturing each of the first to third embodimentsaccording to the disclosure;

FIG. 16 is a schematic view illustrating an LED package including theLED of the disclosure;

FIG. 17 is a diagram illustrating relationship of radiation intensityand light emitting angle of the conventional LED and that of the LED ofthe disclosure;

FIG. 18 is a schematic view illustrating an LED module includingconventional LEDs, in which two adjacent ones of the conventional LEDsare spaced apart from one another by a distance of 1.0 mm; and

FIG. 19 is a schematic view illustrating an LED module including the LEDof the disclosure, in which two adjacent ones of the LEDs of thedisclosure are spaced apart from one another by a distance within arange of 1.05 mm to 1.10 mm.

DETAILED DESCRIPTION

Before the disclosure is described in greater detail, it should be notedthat where considered appropriate, reference numerals have been repeatedamong the figures to indicate corresponding or analogous elements, whichmay optionally have similar characteristics.

Referring to FIG. 3, a first embodiment of a light-emitting diode (LED)according to the disclosure includes a light-transmissive substrate 101,an epitaxial structure, a first insulation layer 106, and a secondinsulation layer 109.

The light-transmissive substrate 101 may be electrically insulating orelectrically conductive based on practical requirements. In certainembodiments, the light-transmissive substrate 101 may be a growthsubstrate for growing the epitaxial structure. Such growth substrate maybe made of materials such as sapphire, silicon carbide, silicon, galliumnitride, aluminum nitride, etc. The light-transmissive substrate 101 hasa first surface, a second surface opposite to the first surface, and aside wall interconnecting the first and second surfaces. The secondsurface is the major light exiting surface of the LED. In certainembodiments, at least a portion of the first surface of thelight-transmissive substrate 101 is formed with a protrusion pattern,which may be irregular or regular. For example, the light-transmissivesubstrate 101 may be a patterned sapphire substrate. A thickness of thelight-transmissive substrate 101 may be within a range of 40 μm to 150μm. For example, when the light-transmissive substrate 101 is relativelythick, the thickness thereof may be within a range of 80 μm to 150 μm.When the light-transmissive substrate 101 is relatively thin, thethickness thereof may be within a range of 40 μm to 80 μm, or evenwithin a range of 40 μm to 60 μm.

A size of the LED may be controlled by a size of the first surface ofthe light-transmissive substrate 101, so as to meet miniaturizationrequirements of LEDs for applications in various electronic devices. Incertain embodiments, the first surface of the light-transmissivesubstrate 101 has a length that ranges from 40 μm to 300 μm, such as 100μm to 300 μm, 100 μm to 200 μm, or even not greater than 100 μm (e.g.,40 μm to 100 μm). An area of the first surface (i.e., an area of ahorizontal cross-section of the light-transmissive substrate 101) may beequal to or lower than 90000 μm² (such as 10000 μm² to 50000 μm), oreven equal to or lower than 10000 μm², and greater than 2000 μm (e.g.,50 μm×50 μm).

The epitaxial structure is disposed on the first surface of thelight-transmissive substrate 101. At least a portion of the firstsurface of the light-transmissive substrate 101 is covered by theepitaxial structure. A remaining portion of the first surface that isnot covered by the epitaxial structure serves as a cutting region for acutting process to be conducted. The epitaxial structure may besurrounded by the cutting region. The epitaxial structure has an uppersurface opposite to the first surface, and a side wall interconnectingthe upper surface and the first surface.

The epitaxial structure includes a first-type semiconductor layer 102,an active layer 103, and a second-type semiconductor layer 104 that aresequentially disposed on the first surface of the light-transmissivesubstrate 101 in such order. Each of the first-type semiconductor layer102, the active layer 103, and the second-type semiconductor layer 104may be made of a group III-IV nitride semiconductor material such as anitride-based semiconductor material. Examples of the nitride-basedsemiconductor material may include, but are not limited to, AlN, GaN,InN, and combinations thereof. The first-type semiconductor layer 102includes one of an N-type dopant (e.g., Si, Ge, and Sn) and a P-typedopant (e.g., Mg, Sr, and Ba), and the second-type semiconductor layer104 includes the other one of the N-type dopant and P-type dopant. Inthis embodiment, the first-type semiconductor layer 102 includes theN-type dopant, and the second-type semiconductor layer 104 includes theP-type dopant. The active layer 103 may include a multiple quantum wellstructure, and may be made of a predetermined nitride-based materialbased on a desired wavelength of light to be emitted therefrom.

The epitaxial structure may include at least one recess which extendsthrough the second semiconductor layer 104 and the active layer 103, andwhich terminates at the first semiconductor layer 102. That is, therecess partially exposes the first semiconductor layer 102, and isdefined by side walls of the second semiconductor layer 104 and theactive layer 103, and an exposed surface of the first semiconductorlayer 102. Alternatively, the epitaxial structure may be formed with atleast one mesa structure such that a portion of the first semiconductorlayer 102 is not covered by the active layer 103 or the secondsemiconductor layer 104. In this embodiment, as shown in FIG. 3, theepitaxial structure is formed with one mesa structure.

The first insulation layer 106 covers the side wall and the uppersurface of the epitaxial structure. The first insulation layer 106includes an upper covering part 1061 and a side covering part 1062 whichrespectively cover the upper surface and the side wall of the epitaxialstructure. The first insulation layer 106 may also cover a portion ofthe first semiconductor layer 102 exposed from the mesa structure of theepitaxial structure. As such, the light emitted from the active layer103, when reaching the first insulation layer 106, may be reflected backinto the epitaxial structure by the first insulation layer 106, and thenmay exit from the second surface of the light-transmissive substrate101, thereby reducing loss of light exiting from the upper surfaceand/or the side wall of the epitaxial structure.

The upper covering part 1061 of the first insulation layer 106 may havea geometric thickness represented by a formula of 2kλ/4n, where k is apositive integer, λ is a wavelength of light emitted from the activelayer 103 of the epitaxial structure, and n is a refractive index of thefirst insulation layer 106. A geometric thickness of the upper coveringpart 1061 along a direction perpendicular to the upper surface may bedifferent from a geometric thickness of the side covering part 1062along a direction perpendicular to the side wall of the epitaxialstructure. In certain embodiments, the thickness of the side coveringpart 1062 is 40% to 90% of the thickness of the upper covering part1061.

The first insulation layer 106 may include a distributed Bragg reflectorstructure which contains multiple pairs of layers, each pair including afirst layer having a first refractive index and a second layer having asecond refractive index lower than the first refractive index. The firstlayers and the second layers in the distributed Bragg reflectorstructure are alternately stacked. In certain embodiments, each of thefirst layers is made of a material selected from the group consisting ofTiO₂ and Ti₂O₅, and each of the second layers is made of a materialselected from the group consisting of an oxide of silicon (SiO_(x)) anda fluoride of magnesium (MgF_(x)). For example, the distributed Braggreflector structure includes alternately stacked TiO₂ and SiO₂ layers.Theoretically, in order to reflect 80% or even 90% of the light emittedfrom the active layer 103, each of the first and second layers in thedistributed Bragg reflector structure of the first insulation layer 106may have an optical thickness that is equal to an integer multiple ofone-quarter of an emission peak wavelength of the light emitted from theactive layer 103 (i.e., λ/4). The distributed Bragg reflector structureof the first insulation layer 106 may include 4 to 20 pairs of the firstand second layers. In addition, in certain embodiments, an uppermostportion of the first insulation layer 106 may be made of a nitride ofsilicon (SiN_(x)), so as to protect the LED from moisture.

The second insulation layer 109 covers a portion of the first surface(i.e., the cutting region) of the light-transmissive substrate 101 thatis not covered by the epitaxial structure and the first insulation layer106. The second insulation layer 109 has a light-transmittance greaterthan that of the first insulation layer 106. In certain embodiments, thesecond insulation layer 109 has a light transmittance that is at least90%. The light emitted from the epitaxial structure, when passingthrough the side wall of the epitaxial structure, may reach and passthrough the second insulation layer 109 located at the cutting region ofthe LED and then may exit from the second surface of thelight-transmissive substrate 101, so as to effectively reduce light lossat the cutting region, thereby increasing a light extraction efficiencyof the LED.

In this embodiment, the second insulation layer 109 is made of amaterial different from that of the first insulation layer 106. Thesecond insulation layer 109 may have a single-layer structure. Forexample, the second insulation layer 109 may be made of a materialselected from the group consisting of an oxide of silicon (SiO_(x)), anitride of silicon (SiN_(x)), magnesium fluoride, and Al₂O₃. The secondinsulation layer 109 may have a geometric thickness represented by aformula of (2k−1)λ/4n, where k is a positive integer, λ is a wavelengthof light emitted from the epitaxial structure, and n is a refractiveindex of the second insulation layer 109. For example, when the secondinsulation layer 109 is made of SiO₂ having a refractive index n of1.46, a wavelength of light emitted from the epitaxial structure iswithin a range of 440 nm to 480 nm, and k=1, the geometric thickness ofthe second insulation layer 109 may be estimated to be within a range of75 nm to 82 nm.

The epitaxial structure may further include a contact electrode 105which is disposed between the second-type semiconductor layer 104 andthe first insulation layer 106, and which is capable of forming an ohmiccontact with the second-type semiconductor layer 104. The contactelectrode 105 may be a light-transmissive electrode made of one of anelectrically conductive oxide, a metallic material (e.g., Ni or Au), anda combination thereof. The electrically conductive oxide may be furtherdoped with dopants. Examples of the electrically conductive oxide mayinclude, but are not limited to, indium tin oxide (ITO), zinc oxide(ZnO), indium-tin-zinc oxide, indium zinc oxide, tin-zinc oxide,indium-gallium-tin oxide, indium-gallium oxide, gallium-zinc oxide,aluminum-doped zinc oxide, and fluorine-doped tin oxide. When thecontact electrode 105 is made of the electrically conductive oxide, arelatively high efficiency of ohmic contact between the contactelectrode 105 and the second-type semiconductor layer 104 may beachieved. For example, a contact resistance between the second-typesemiconductor layer 104 and the contact electrode 105 made of ITO or ZnOis lower than a contact resistance between the second-type semiconductorlayer 104 and the contact electrode 105 made of the metallic material.Therefore, the contact electrode 105 made of the electrically conductiveoxide is capable of decreasing a forward voltage (Vf) of the LED,thereby increasing the light extraction efficiency thereof. In addition,as compared to the contact electrode 105 made of the metallic material,the contact electrode 105 made of the electrically conductive oxide isless prone to peeling, and therefore the resultant LED may have a higherreliability.

The LED may further include a first electrode 107 and a second electrode108. The first insulation layer 106 may be formed with a first hole toexpose the first-type semiconductor layer 102, and a second hole toexpose the upper surface of the epitaxial structure. The first electrode107 is formed in the first hole and is electrically connected to thefirst-type semiconductor layer 102. The second electrode 108 is formedin the second hole and is electrically connected to the second-typesemiconductor layer 104. In this embodiment, the second hole exposes thecontact electrode 105, and the second electrode 108 is electricallyconnected to the second-type semiconductor layer 104 through the contactelectrode 105. Each of the first and second electrodes 107, 108 mayinclude a metallic contact layer and a metallic eutectic layer. Aminimal horizontal distance between the first and second electrodes 107,108 on the first insulation layer 106 may be 5 μm. In certainembodiments, the contact electrode 105 may be formed with a through holeto expose the second-type semiconductor layer 104, and the secondelectrode 108 may extend into the through hole to contact with thesecond-type semiconductor layer 104. A resistance between the secondelectrode 108 and the second-type semiconductor layer 104 may be higherthan a resistance between the second electrode 108 and the contactelectrode 105, so as to reduce a current crowding effect at an interfacebetween the second electrode 108 and the second-type semiconductor layer104.

Referring to FIG. 4, a second embodiment of the LED according to thedisclosure is similar to the first embodiment, except that in the secondembodiment, the second insulation layer 109 further includes anextension covering part 1091 which covers the upper surface and the sidewall of the epitaxial structure, and which is disposed between theepitaxial structure and the first insulation layer 106.

In the second embodiment, the first insulation layer 106 containing adistributed Bragg reflector structure may further include an interfacelayer (not shown in the figures) to improve a quality of the distributedBragg reflector structure. The interface layer may be made of SiO₂, andmay have a thickness within a range of 0.2 μm to 1.0 μm. When the firstinsulation layer 106 includes alternately stacked TiO₂/SiO₂ layers(i.e., the distributed Bragg reflector structure) which are deposited onthe interface layer, such interface layer may directly serve as thesecond insulation layer 109. With the second insulation layer 109 (i.e.,the interface layer) disposed on the cutting region, the lightextraction efficiency of the LED may be improved, and a compressivestrain at the cutting region may be reduced, thereby reducing bowing ofthe LED and improving a quality thereof.

Referring to FIG. 5, a third embodiment of the LED according to thedisclosure is similar to the first embodiment except that, in the thirdembodiment, the first and second insulation layers 106, 109 are made ofan identical material. Each of the first and second insulation layers106, 109 is made of a material selected from the group consisting of anoxide of silicon (SiO_(x)), a nitride of silicon (SiN_(x)), magnesiumfluoride, and Al₂O₃. Each of the first and second insulation layers 106,109 has a refractive index lower than those of the first-typesemiconductor layer 102, the active layer 103 and the second-typesemiconductor layer 104.

The thickness of the first insulation layer 106 is not limitedspecifically, and may be modified based on practical requirements. Inthis embodiment, the first insulation layer 106 has a thickness (D1)that is greater than a thickness (D2) of the second insulation layer109. The second insulation layer 109 may be obtained by a thinningprocess (i.e., thinning a portion of the first insulation layer 106which is originally disposed on the cutting region). When the LED has athickness of not greater than 80 μm, the geometric thickness of thesecond insulation layer 109 (i.e., D2) is not greater than 50 nm, so asto effectively release compressive strain at the cutting region of theLED.

In this embodiment, the first insulation layer 106 has a geometricthickness represented by the formula of 2kλ/4n, and the secondinsulation layer 109 has a geometric thickness represented by theformula of (2k−1)λ/4n, where k is a positive integer, λ is a wavelengthof light emitted from the epitaxial structure, and n is a refractiveindex of the material for making the first and second insulation layers106, 109. Specifically, when the first and second insulation layers 106,109 are made of SiO₂ having a refractive index of 1.46, a wavelength oflight emitted from the epitaxial structure is within a range of 440 nmto 480 nm, and k=1, the geometric thickness of the first insulationlayer 106 (i.e., D1) is within a range of 150 nm to 165 nm, and thegeometric thickness of the second insulation layer 109 (i.e., D2) iswithin a range of 75 nm to 82 nm.

Referring to FIG. 6, a fourth embodiment of the LED according to thedisclosure is similar to the first embodiment except that, in the fourthembodiment, the second insulation layer 109 is formed with at least oneopening 110. The opening 110 may be formed in a loop shape, a stripshape, or a pinhole shape. When the opening 110 is formed in a stripshape, a width thereof may range from 2 μm to 10 μm. When the opening110 is formed in a loop shape or a pinhole shape, a diameter thereof mayrange from 2 μm to 10 μm. When the second insulation layer 109 is formedwith a plurality of the openings 110, a distance between two adjacentones of the openings 110 may range from 2 μm to 5 μm.

By formation of the opening(s) 110 in the second insulation layer 109,the light emitted from the side wall of the epitaxial structure maydirectly pass through the second insulation layer 109 at the cuttingregion of the LED through the openings 110, which may increase the lightextraction efficiency of the LED. In addition, the openings 110 are alsocapable of reducing the compressive strain at the cutting region,thereby reducing bowing and breakage of the LED.

It should be noted that the second insulation layer 109 of the second orthird embodiment of the LED may also be formed with the opening(s) 110,so as to increase the light extraction efficiency of the LED.

Referring to FIGS. 7 to 15, a method for manufacturing one of the firstto third embodiments of the LEDs according to the disclosure includesthe following steps.

As shown in FIG. 7, the epitaxial structure is provided on thelight-transmissive substrate 101. The epitaxial structure includes thefirst-type semiconductor layer 102, the active layer 103, and thesecond-type semiconductor layer 104 that are formed on thelight-transmissive substrate 101 in such order.

As shown in FIG. 8, the epitaxial structure is etched using a photomaskto form a plurality of the recesses each extending through thesecond-type semiconductor layer 104 and the active layer 103 andpartially exposing the first-type semiconductor layer 102. As shown inFIG. 9, the first-type semiconductor layer 102 exposed from the recessesis further etched using a photomask to partially expose the firstsurface of the light-transmissive substrate 101 (i.e., the cuttingregion), thereby forming a plurality of LED units separated by thecutting region, each having a mesa structure.

As shown in FIG. 10, for each of the LED units, the contact electrode105 (e.g., made of ITO) is formed on the second-type semiconductor layer104 opposite to the active layer 103 by a vapor deposition process or asputtering process. In certain embodiments, the contact electrode 105may be formed with at least one electrode hole to partially expose thesecond-type semiconductor layer 104.

As shown in FIG. 11, for each of the LED units, the first insulationlayer 106 is formed by a vapor deposition process or a sputteringprocess to cover the upper surface of the epitaxial structure (i.e., thecontact electrode 105), the side wall of the epitaxial structure, andthe exposed first surface of the light-transmissive substrate 101. Thefirst insulation layer 106 is formed with the first hole and the secondhole. The first hole partially exposes the first-type semiconductorlayer 102, and the second hole partially exposes the contact electrode105.

As shown in FIG. 12, for each of the LED units, the first and secondelectrodes 107, 108 are respectively formed in the first and secondholes, such that the first electrode 107 is electrically connected tothe first-type semiconductor layer 102, and the second electrode 108 iselectrically connected to the second-type semiconductor layer 104through the contact electrode 105. In certain embodiments, when thecontact electrode 105 is formed with the electrode hole, the secondelectrode 108 can directly contact with the second-type semiconductorlayer 104 via the electrode hole of the contact electrode 105.

Referring to FIGS. 13 to 15, for each of the LED units, the secondinsulation layer 109 is formed at the cutting region. To be specific,for making the first embodiment of the LED, a portion of the firstinsulation layer 106 disposed on the cutting region is entirely removedto expose the first surface of the light-transmissive substrate 101, andthen the second insulation layer 109 made of a material different fromthat of the first insulation layer 106 is formed on the exposed portionof the light-transmissive substrate 101 (see FIG. 13).

As shown in FIG. 14, for making the second embodiment of the LED, aportion of the distributed Bragg reflector structure (alternatelystacked TiO₂/SiO₂ layers) of the first insulation layer 106 that islocated at the cutting region is partially removed, such that theinterface layer made of SiO₂ (not shown) remains on the cutting regionand serves as the second insulation layer 109. The interface layer maybe further thinned to have a thickness that exhibits a desired lighttransmittance. Alternatively, a portion of the first insulation layer106 disposed on the cutting region may be entirely removed to expose thefirst surface of the light-transmissive substrate 101, and then thesecond insulation layer 109 is formed on the exposed first surface ofthe light-transmissive substrate 101.

As shown in FIG. 15, for making the third embodiment of the LED, aportion of the first insulation layer 106 disposed on the cutting regionis thinned to meet requirements for light transmittance, so as to obtainthe second insulation layer 109. That is, the second insulation layer109 is made of a material identical to that of the first insulationlayer 106, and has a thickness smaller than that of the first insulationlayer 106.

Finally, a cutting process is performed on the cutting region, so as toseparate the LED units from one another, thereby obtaining a pluralityof the LEDs of this disclosure. The cutting process may be conducted bya laser scanning procedure to form a plurality of explosion points inthe light-transmissive substrate 101 underneath the cutting region,followed by dicing along the cutting region using an LED wafer breakerto excite the explosion points, thereby obtaining the separated LEDs.

The LED of the disclosure, which has a relatively high luminance, can bewidely applied in various fields such as backlight display device andsemiconductor packaging. For example, referring to FIG. 16, an LEDpackage according to the disclosure includes a package substrate 30, andat least one LED of the disclosure which is disposed on the packagesubstrate 30. The package substrate 30 may be an electrically insulatingsubstrate, such as a substrate commonly used in RGB display screens orbacklight display devices. A first electrode layer 301 and a secondelectrode layer 302 are spacedly formed on the package substrate 30 in amanner such that the first and second electrode layers 301, 302 areelectrically isolated from each other. The first and second electrodelayers 301, 302 of the LED package are respectively electricallyconnected to the first electrode 107 of the LED via a first connectingmember 303, and to the second electrode 108 of the LED via a secondconnecting member 304. Each of the first and second connecting members303, 304 may be made of a solder material such as eutectic solder andreflow solder, but is not limited thereto. It can be noted that, thelight emitted from the active layer 103 (illustrated as arrow lines inFIG. 16) can pass through the first insulation layer 106 and the secondinsulation layer 109 to exit therefrom without undergoing secondaryreflection. Referring to FIG. 17, the LED of the disclosure exhibits ahigher intensity of light emitted at a relatively high light-emittingangle as compared to that of the conventional LED as shown in FIG. 1.

When used in RGB display or backlight modules, a plurality of LEDs aregenerally arranged in a matrix to form a light-emitting array.Therefore, the disclosure also provides an LED module which includes thepackage substrate 30 and the light-emitting array disposed on thepackage substrate 30. The matrix of the light-emitting array may includeat least one column of red LEDs, at least one column of green LEDs, andat least one column of blue LEDs. Alternatively, all of the LEDs of thelight-emitting array may be the same LEDs (e.g., blue LEDs).

According to this disclosure, a display device (e.g., liquid-crystaldisplay (LCD) display device) including a plurality of theabovementioned LED modules is provided such that high-dynamic range(HDR) images achieve satisfactory display effects. A contrast ratio ofthe display device can be controlled by turning on or off a specific oneof the LEDs in the LED modules. In addition, since the LED of thisdisclosure exhibits an increased luminance, a total luminance of thedisplay device may be further improved.

Referring to FIG. 18, when the LED module includes the conventional LEDsof FIG. 1, two adjacent ones of the conventional LEDs are spaced apartfrom one another by a distance of e.g., 1.0 mm, so as to compensate forlight loss at the cutting region of the LEDs and maintain a totalluminance of the LED module. In comparison, as shown in FIG. 19, sincethe LED module includes the LEDs of the disclosure which exhibit ahigher light extraction efficiency, two adjacent ones of the LEDs may bespaced apart from each other by a larger distance, such as 5% to 10%greater than that of the conventional LEDs (i.e., 1.05 nm to 1.10 nm),so that the LED module of FIG. 19 achieves the same total luminance asthat of the conventional LED module of FIG. 18. In other words, thenumber of LEDs required in the LED module of FIG. 19 may be reduced by5% to 10% compared to that of the LED module of FIG. 18, therebylowering a manufacture cost thereof.

In sum, by virtue of the second insulation layer 109 which is formed onthe cutting region of the LED, and which has a light transmittancegreater than that of the first insulation layer 106, secondary lightreflection by the second insulation layer 109 at the cutting region maybe reduced, and the light extraction efficiency of the LED of thisdisclosure may be increased. In addition, by formation of the opening(s)110 in the second insulation layer 109, the light extraction efficiencyand luminance of the LED of this disclosure may be further improved.Furthermore, by controlling the thickness of the second insulation layer109 to be smaller than that of the first insulation layer 106 and/orforming the opening(s) 110 in the second insulation layer 109, thecompressive strain at the cutting region of the LED may be reduced,thereby reducing bowing of the LED of this disclosure and improving thequality thereof.

In the description above, for the purposes of explanation, numerousspecific details have been set forth in order to provide a thoroughunderstanding of the embodiments. It will be apparent, however, to oneskilled in the art, that one or more other embodiments may be practicedwithout some of these specific details. It should also be appreciatedthat reference throughout this specification to “one embodiment,” “anembodiment,” an embodiment with an indication of an ordinal number andso forth means that a particular feature, structure, or characteristicmay be included in the practice of the disclosure. It should be furtherappreciated that in the description, various features are sometimesgrouped together in a single embodiment, figure, or description thereoffor the purpose of streamlining the disclosure and aiding in theunderstanding of various inventive aspects, and that one or morefeatures or specific details from one embodiment may be practicedtogether with one or more features or specific details from anotherembodiment, where appropriate, in the practice of the disclosure.

While the disclosure has been described in connection with what areconsidered the exemplary embodiments, it is understood that thisdisclosure is not limited to the disclosed embodiments but is intendedto cover various arrangements included within the spirit and scope ofthe broadest interpretation so as to encompass all such modificationsand equivalent arrangements.

What is claimed is:
 1. A light-emitting diode, comprising: alight-transmissive substrate which has a first surface; an epitaxialstructure which is disposed on said first surface of saidlight-transmissive substrate, and which has an upper surface opposite tosaid first surface, and a side wall interconnecting said upper surfaceand said first surface; a first insulation layer which covers said sidewall and said upper surface of said epitaxial structure; and a secondinsulation layer which covers a portion of said first surface of saidlight-transmissive substrate that is not covered by said epitaxialstructure and said first insulation layer, said second insulation layerhaving a light transmittance greater than that of said first insulationlayer.
 2. The light-emitting diode according to claim 1, wherein saidfirst and second insulation layers are made of an identical material,and said first insulation layer has a thickness that is greater than athickness of said second insulation layer.
 3. The light-emitting diodeaccording to claim 2, wherein the thickness of said second insulationlayer is not greater than 50 nm.
 4. The light-emitting diode accordingto claim 2, wherein each of said first and second insulation layers ismade of a material selected from the group consisting of an oxide ofsilicon, a nitride of silicon, magnesium fluoride, and Al₂O₃.
 5. Thelight-emitting diode according to claim 1, wherein said first insulationlayer includes an upper covering part and a side covering part whichrespectively cover said upper surface and said side wall of saidepitaxial structure, said upper covering part has a geometric thicknessrepresented by a formula of 2kλ/4n, where k is a positive integer, λ isa wavelength of light emitted from said epitaxial structure, and n is arefractive index of said first insulation layer.
 6. The light-emittingdiode according to claim 1, wherein said second insulation layer has ageometric thickness represented by a formula of (2k−1)λ/4n, where k is apositive integer, λ is a wavelength of light emitted from said epitaxialstructure, and n is a refractive index of said second insulation layer.7. The light-emitting diode according to claim 1, wherein said first andsecond insulation layers are made of different materials.
 8. Thelight-emitting diode according to claim 7, wherein said first insulationlayer is a distributed Bragg reflector structure which includes multiplepairs of layers, each pair including a first layer having a firstrefractive index and a second layer having a second refractive indexlower than the first refractive index, said first layers and said secondlayers in the distributed Bragg reflector structure beingalternately-stacked.
 9. The light-emitting diode according to claim 8,wherein each of said first layers is made of a material selected fromthe group consisting of TiO₂ and Ti₂O₅, and each of said second layersis made of a material selected from the group consisting of an oxide ofsilicon and a fluoride of magnesium.
 10. The light-emitting diodeaccording to claim 7, wherein said second insulation layer is made of amaterial selected from the group consisting of an oxide of silicon, anitride of silicon, magnesium fluoride, and Al₂O₃.
 11. Thelight-emitting diode according to claim 7, wherein said secondinsulation layer has a single-layer structure.
 12. The light-emittingdiode according to claim 7, wherein said second insulation layer furtherincludes an extension covering part which covers said upper surface andsaid side wall of said epitaxial structure, and which is disposedbetween said epitaxial structure and said first insulation layer. 13.The light-emitting diode according to claim 1, wherein said firstinsulation layer includes an upper covering part and a side coveringpart which covers said upper surface and said side wall of saidepitaxial structure, and a geometric thickness of said upper coveringpart along a direction perpendicular to said upper surface is differentfrom a geometric thickness of said side covering part along a directionperpendicular to said side wall.
 14. The light-emitting diode accordingto claim 13, wherein the thickness of said side covering part is 40% to90% of the thickness of said upper covering part.
 15. The light-emittingdiode according to claim 1, wherein said first surface of saidlight-transmissive substrate has a length that ranges from 40 μm to 300μm.
 16. The light-emitting diode according to claim 1, wherein: saidepitaxial structure includes a first-type semiconductor layer, an activelayer, and a second-type semiconductor layer that are sequentiallydisposed on said first surface of said light-transmissive substrate insuch order; said first insulation layer is formed with a first hole toexpose said first-type semiconductor layer, and a second hole to exposesaid upper surface; and said light-emitting diode further comprises afirst electrode and a second electrode, said first electrode beingformed in said first hole and being electrically connected to saidfirst-type semiconductor layer, said second electrode being formed insaid second hole and being electrically connected to said second-typesemiconductor layer.
 17. The light-emitting diode according to claim 16,wherein said epitaxial structure further includes a contact electrodewhich is disposed between said second-type semiconductor layer and saidfirst insulation layer.
 18. The light-emitting diode according to claim1, wherein said second insulation layer is formed with at least oneopening.
 19. The light-emitting diode according to claim 18, whereinsaid opening is formed in one of a loop shape, a strip shape, and apinhole shape.
 20. The light-emitting diode according to claim 18,wherein said opening has a diameter ranging from 2 μm to 10 μm.
 21. Thelight-emitting diode according to claim 18, wherein said secondinsulation layer is formed with a plurality of the openings, a distancebetween two adjacent ones of said openings ranging from 2 μm to 5 μm.22. A light-emitting diode package, comprising: a package substrate; andat least one light-emitting diode as claimed in claim 1, which isdisposed on said package substrate.
 23. A light-emitting diode module,comprising: a package substrate; and a light-emitting array which isdisposed on said package substrate and which includes a plurality oflight-emitting diodes that are arranged in a matrix, at least one ofsaid light-emitting diodes being the light-emitting diode as claimed inclaim
 1. 24. The light-emitting diode module according to claim 23,wherein said matrix includes at least one column of red light-emittingdiodes, at least one column of green light-emitting diodes, and at leastone column of blue light-emitting diodes.
 25. The light-emitting diodeaccording to claim 23, wherein said light-emitting diodes are bluelight-emitting diodes.
 26. A display device, comprising: a plurality oflight-emitting diode modules as claimed in claim 23.